Series submersible motor pump



Nov. 19, 1940. A. HOLLANDER SERIES SUBMERSIBLE MOTOR PUMP 3 Sheets-Sheetl Filed March 4, 1938 INVENTOR BY fl/aaar' Ho//a/2der ATTORNEY Nov. 19,1940. HQLLANDER 2,221,798

SERIES SUBMERSIBLE MOTOR PUMP Filed March 4, 19318 3 Sheets-Sheet 2ATTORNEY Nov. 19, 1940. A. HOLLANDER 2 L SERIES SUBMERSIBLE MOTOR PUMPFiled March 4, 1938 3 Sheets-Sheet 3 LINE l l u FUSED l NNE v fifiw 74PUSH BUTTON 78 f STATION/ 7 ii 102 x fi RELAY 80 .720 9,% 95 )TME DELAY9 RELAY v I OILTESTFZQEF COIL lNmcATon/ WATER LEvEb 110 5| ATTORNEYPatented Nov. 19, 1940 UNITED STATES PATENT OFFICE SERIES SUBMIERSIBLEMOTOR PUMP Application March 4, 1938, Serial No. 193,968

3 Claims.

This invention relates generally to submersible motor pumps, and isdirected particularly to the provision of a plurality of submersiblemotorpump units in series.

The development of submersible motor-pum units for pumping deep waterwells has in recent years been confined mainly to the perfection of asubmersible electric motor for direct connection to a multi-stagecentrifugal pump, to reshort section of large diameter and a lowersection of decreased diameter. The water-bearing formation may be atconsiderable depth, but of sufiicient pressure to provide an originalpumping level at only a relatively shallow depth. In the course of time,however, the pumping level may be gradually lowered until it stands aconsiderable distance below the large diameter portion of the well.

The final depth of the pumping level and the small diameter of the lowerportion of the well may be such as to make it impracticable to install asingle submersible motor-pump unit of sufficien-t head and volumecapactiy.

Under these circumstances, I propose to utilize two or more submersiblemotor-pump units, one within the lower, small diameter portion and atleast one booster unit in the upper, enlarged portion of the well. Asmall unit, of sufiicient head capactiy to lift the 'water to thebooster unit, may be installed in the lower, reduced portion of thewell. If the water level conditions are known before the well isdrilled, the depth of the large diameter section may be predetermined sothat a booster unit installed near the lower end thereof will besubstantially midway between the surface and the lower unit, thusdividing the total lift into two substantially equal stages and enablingthe use of identical motor-pump units. A single unit may be installedinitially, until the pumping level has been lowered beyond the headcapacity of one unit, and a second unit may then be added.

A principal object of this invention is to provide a series submersiblemotor-pump installation for wells having an upper portion of relativelylarge diameter and a lower portion of reduced diameter, wherein asubmersible motorpump unit is installed in the lower, reduced portionand a second unit is installed in the upper, enlarged portion andconnected in series with the lower unit to serve as a booster therefor.

An arrangement permitting the use of a plurality of units 'isparticularly advantageous in cases where the'initial and finalpumpinglevels are not known. In such cases a single submersiblemotor-pump unit may be installed and periodically lowered as the pumpinglevel lowers, and when the depth exceeds the'head capactiy of the unit asecond unit may be added instead of substituting a larger unit for theoriginal one.

Various schemes have been proposed heretofore for connecting submersiblemotor-pump units in series, but such schemes are all defective in onerespect or another, because of practical operating difiiculties whichhave been overlooked or under-estimated. A further object of thisinvention is to provide a series submersible motorpump arrangement whichwill give trouble-free operation over a long period of time, and whichpermits utilization of identical motor-pump units which have been provensuccessful.

The motor-pump unit under consideration consists generally of asubmersible electric motor having its rotor shaft direct-connected tothe pump shaft. The motor is encased in a fluidtight housing which isfilled with a dielectric liquid, pressure equalizing means beingprovided whereby the pressure within .the housing is equal to that ofthe liquid in which the housing is immersed. When the unit is immersedin the well liquid, the flow of the latter past the motor housing servesto cool the motor. A liquid seal is provided where the rotor shaftextends through the housing, the seal being exposed on opposite. sidesto the well liquid and the dielectic liquid Within the housing. Electriccurrent is conducted to the motor from the surface through an insulatedand fluid-tight cable having fluid-tight connection to the motorhousing. The interior of the cable is in communication with the interiorof the motor housing, whereby the dielectric liquid filling the housingmay rise in the cable, the hydrostatic head of the well liquid beingthus balanced internally of the cable as well as within the motorhousing.

In order to insure trouble-free operation of the upper motor-pump unitwhen it is located a sufficient distance above the lower unit so as notto be immersed in the well liquid, it is necessary to simulate as nearlyas possible the conditions of operation when submerged. In other words,the motor housing should be water-cooled, the internal and externalpressures should be balnaced, the pressure should be relatively low soas to avoid forcing the dielectric liquid upwardly within the cable at apressure greatly in excess of the external pressure, and the liquid sealshould be exposed to well liquid at substantially the pressure exertedon the housing.

A further object of the invention is to provide a plurality ofsubmersible motor-pump units in series, wherein all of the units operateunder substantially the same conditions.

A still further object is the provision of watercooling for asubmersible motor when operating above the level of the well liquid.

A still further object is to provide a series submersible motor-pumpassembly wherein the upper unit may be located above the well liquidlevel and be cooled by circulation of well liquid thereover, the coolingliquid being supplied by the discharge from the lower unit and being ata relatively low pressure irrespective of the discharge pressure.

Standard submersible motors and pumps are not intended to support anygreat weight, and hence if a motor-pump unit is to be interposed in thedischarge column above the lower unit and separated therefrom by a lowersection of discharge column, it is necessary to provide for supportingthe lower section of column and the lower motor-pump unit from the uppersection of column independently of the upper motorpump unit. A stillfurther object of this invention is to provide, in an assembly asreferred to herein, a supporting connection between the upper and lowersections of the discharge column and bridging the upper motor-pump unit,thereby relieving the latter of the weight of the subjacent parts.

In a series motor-pump installation wherein the upper unit serves as abooster and the lower unit is incapable alone of pumping to the surface,it is useless to operate either unit unless the other one is operating.It is also dangerous to operate the upper unit unless it is receivingliq- -uid from the lower one, especially if the pump bearings arelubricated by the liquid being pumped. If run dry for any length of timethe bearings will overheat and seize, overloading the motor.

For the latter reason, the upper unit should not be started until thedischarge from the lower unit reaches it, thus requiring a time intervalbetween the starting of the lower and upper units.

A still further object of this invention is to provide a seriesmotor-pump installation wherein suitable controls are provided forstopping both motors if a condition adverse to proper operation ariseswithin either motor.

A still further object is to provide a series motor-pump installation inwhich provision is made for delaying the starting of the upper unituntil sufficient time has elapsed for the discharge of the lower unit toreach the upper unit.

A still further object is to provide a series motor-pump installation inwhich the motor of the lower unit is started manually, and in which themotor of the upper unit is started automatically at the end of apredetermined time interval following the starting of the lower motor.

A still further object is to provide a series submersible motor-pumpinstallation wherein themotor of the upper unit is cooled by circulationof discharge fluid from the lower unit, and wherein means are providedfor stopping both units in the event the cooling means fails to functionproperly.

Other objects and advantages will be apparent from the followingdescription, taken in conjunction with the accompanying drawings,wherein:

Fig. 1 is an elevation of the upper portion of the upper motor-pumpunit, with parts broken away;

Fig. 2 is an elevation of the lower portion of the upper unit and thelower discharge column;

Fig. 3 is an elevation of the lower motor-pump unit;

Fig, 4 is an elevational view of the two units combined, as they appearwhen viewed from the left of Figs. 1 to 3;

Fig. 5 is a horizontal section taken substantially on line 55 of Fig. 1;

Fig. 6 is a horizontal section taken substantially on line 6--6 of Fig.2; and

Fig. 7 is aiwiring diagram of interconnected starting and motorprotection circuits for the motors.

Referring to the drawings and particularly to Fig. 4, the assembly isshown installed in a well equipped with an upper casing I of relativelylarge diameter, and a lower casing 2 of reduced diameter, the twocasings being joined by a conical reducer 3. An upper discharge column 4extends to the surface where it is suitably anchored to support theweight of the entire assembly. The upper motor-pump unit, generallydesignated 5, is connected to the lower end of the column 4, and isshown as disposed within the upper casing l adjacent the lower endthereof. A laterally offset connector pipe 6 is connected to the suctioninlet of the pump of the upper unit, and extends downwardly to a pointbelow the motor of the upper unit, where it merges with a lowerdischarge column 1 extending downwardly within the lower reduced casing2 to the point at which it is desired to locate the lower motor-pumpunit. The latter, generally designated I0, is secured to and suspendedfrom the lower end of the column I.

The lower motor-pump unit I0 is preferably, although not necessarily,similar to that shown and described in the application of AladarHollander and Vaino A. Hoover, Serial No. 178,741, filed December 8,1937, for Submersible motor assembly, now matured into U. S. LettersPatent No. 2,171,749, dated September 5, 1939. It comprises generally anelectric motor encased within a fluid-tight housing l2 connected to thelower end of an adapter l3. The latter is bolted to the lower end of astrainer l4 through which well fluid is drawn to the pump. A suctionpiece 15 is interposed between the strainer and the lowermost of aplurality of pump bowls l6, herein shown as two in number in order toconserve space. It will be appreciated, however, that any desired numberof stages may be provided. up to the limitations imposed by the motorCZLIJM' lt/Y as determined by the casing diameter. The rotor shaft ofthe motor extends through the upper end of the housing l2 and is coupledto the pump shaft, a suitable seal (not shown) being provided where theshaft projects through the housing. The uppermost bowl I6 is secured toa discharge piece I! which in turn is connected to an offset flange I8secured to the lower end of the discharge column I. The offset flangedisplaces the discharge column eccentrically of the axis of the motorand pump to provide adequate space for the motor cable while permittingthe use of a discharge column'of sufficient capacity.

A motor cable 2| extends from the surface to the motor, the cable beingfluid-tight and being 5 connected in fluid-tight relation to the motorhousing by a terminal box 22. A balance tube 23 extends from the lowerend of the motor housing to the adapter 13, and establishescommunication between the interior of the housing and the well liquidwhereby the pres-sure within the housing equals the hydrostatic pressureof the well liquid at the point in the well where the motor is located.

In the type of motor-pump unit referredto herein, the motor housing isfilled with a dielectric liquid. The interior of the cable 2| is incommunication with the interior of the motor housing through theterminal box, as shown in Fig. 2

of the aforementioned application of Aladar Hollander and Vaino A.Hoover. The dielectric liquid will be forced upwardly within the cableby the pressure of the well liquid and the pressures will thus bebalanced internally and externally of the cable.

It is highly desirable, although not absolutely necessary, that themotor of the upper unit be identical with that of the lower unit, andthat it be operated under conditions simulating as closely as possiblethe conditions under which the lower motor operates. The constructionwhereby this is accomplished will now be described.

The lower discharge column 1 extends upwardly whatever distance it isdesired to separate the two units, and is connected at its upper end toa special flange member 25. The latter has formed integral therewith aflange provided with laterally projecting bolting ears 26, 26 (Figs. 4,5 and 6) apertured for the reception of a pair .10 of elongatedsuspension rods 21, 21 extending upwardly on either side of the motor ofthe upper unit. The upper ends of the rods extend through apertures incars formed on the lower flange of a special connector 28 of extrastrength. The

weight of the lower discharge column, lower motor-pump unit I 0, and thecolumn of water in the discharge column when pumping is thus transmittedfrom the flange member 25 through the suspension rods 21, 21 to theconnector 28 independently of any structure which may be interposedbetween member 25 and connector 28.

The upper flange of connector 28 is similarly provided with ears throughwhich project a second pair of suspension rods 3|, 3| extending upwardlyto a flange piece 32 secured to the lower end of the upper dischargecolumn 4. Interposed between the connector 28 and the flange piece 32are the pump bowls 33 and discharge piece 34 of the upper motor-pumpunit. It will be apparent that the weight of the subjacent parts is thustransferred from the connector 28 to the upper discharge column 4independently of the pump bowls enabling the use of standard bowls, thebolting flanges of which are of insuflicent strength to withstand suchstresses.

In order to connect the upper end of the'lower discharge column I withthe suction inlet of the upper pump, while at the same time disposingthe upper motor in axial alignment with the pump, the offset connectorpipe ,6 is provided. An eccentric reducer 4| is mounted on the upperflange of the flange member 25 with its lower enlarged end incommunication with the discharge column I. The upper offset reduced endis welded at 42 to the connector pipe 6 which extends upwardly and iswelded at its upper end to a similar offset reduced end 43 formed on aspecial casting 44 bolted to the under side of the connector 28. It willbe observed that the suspension rods relieve the connector pipe of alltensile 5 stresses imposed by the weight of the parts therebelow.

The casting 44 has formed thereon a downwardly projecting cylindricalportion 45 (Figs. 1 and 5) concentric with the upper end thereof. A 10motor adapter 46, similar to that shown at l3 in connection with thelower motor I2, is secured to the lower end of the portion 45, and amotor housing 47 similar to housing I2 is bolted to the lower flange ofthe adapter 46. The shaft of the 15 motor extends through the housinginto the adapter 46, and is there coupled to the pump shaft 48.

A suction passage 5i extends downwardly and outwardly through thecasting 44 from its upper 20 end to the offset reduced end 43, toconnect the connector pipe 3 to the inlet of the upper pump. The twopump units are thereby connected in series.

It is desirable to cool the upper motor by cir- 25 culation of waterover the housing. This could be accomplished by providing an enlargeddischarge pipe surrcunding the motor housing, instead of by-passing thedischarge around the motor. However, as pointed out in the introductory30 remarks, this would give rise to troublesome complications because ofthe discharge pressure. A pressure balance is preferred within andwithout the motor housing, and for various reasons it would beundesirable to subject the interior of 5 the housing to the dischargepressure. Furthermore, wide fluctuations of pressure occur in thedischarge pipe at the location of the upper motor, varying from zerowhen the pumps are idle, to the total head up to the surface when the 40pumps are stopped and the discharge column is full of well liquid.

In order to avpid the difliculties attendant upon such an arrangement, Iprefer to dispose the upper motor outside the discharge column 5 V andwithin a cooling chamber through which well liquid is circulated atconstant head. Referring to Figs. 1 and 2, a cooling chamber 55 isdisposed about the motor housing 41, and comprises an elongatedcylindrical can of slightly 50 greater internal diameter than the outerdiameter of the motor housing, the can being open at its upper end andclosed at its lower end. The can is suspended at its upper end from theupper flange oi the motor housing, by a plurality of 55 L-shaped clipsor brackets 51 (Fig. 5) welded to the upper edge of the can andextending radially inwardly over the lower flange of the adapter 46. Thebrackets are suitably spaced so as to be engaged by certain of the boltssecuring the 60 adapter and motor housing in assembled relation. Ableeder pipe 58 is connected to the oiTset portion 43 of the casting 44at 59, and extends downwardly into the cooling can to a point below themotor housing 41, whereby a small po r 5 tion of the well liquid will bebled from the discharge pipe into the cooling can where it willcirculate upwardly around the motor housing and overflow at the top ofthe can. The amount of cooling water required would be negligible, inthe 70 neighborhood of one or two gallons per minute for a 12-inch H. P.motor.

The upper motor receives electrical energy from the surface through acable 6| similar to the cable 2i leading to the lower motor. A ter- 75minal box 62 connects the cable 8| in fluid-tight relation to the motorhousing 41, and in order to accommodate the terminal box in the coolingcan, an outwardly projecting pocket 83 is formed on the can, as shown inFigs. 4 and 5.

The pump shaft 48 extends through a stufllng box 88 between the interiorof the cylindrical extension 45 and the inlet passage 5| in the casting44, the chamber formed within the extension 45 serving as a drainchamber for any leakage past the stuffing box. The chamber communicatesat its lower end with the interior of the adapter 46, thus insuring thatthe liquid seal around the motor shaft operates exposed to water on theouter side, in the same manner as though the motor housing werecompletely submerged. Overflow outlets 61 are provided in extension 45to prevent the building up of pressure within the chamber and theadapter. A balance tube 68 similar to the balance tube 23 on the lowermotor extends from the lower end of housing 41 to the adapter 48, toprovide a balance of pressures internally and externally of the housing.

The conductor cables 2| and GI extend to the surface, where they areconnected to suitable starting and safety cut-out controls. Preferably,the two motors have separate starting switches, with a time-delay relayin the circuit of the upper motor whereby a definite time interval willelapse between the starting of the lower motor and starting the uppermotor, the time interval being sufiicient to enable the discharge of thelower motor to reach the upper pump before the latter is started.

From the foregoing description, it will be apparent that a simple andpractical assembly of submersible motor-pump units has been provided.The units may be identical, and the upper unit 40 operates underconditions closely simulating submerged operation. By the provision ofsupporting connections between the sections of the discharge columnindependent of the upper motorpump unit, standard motor and pump partsmay 45 .be used.

Standardization of units is made possible by a series connection asdescribed, inasmuch as any number of standard units may be connectedtogether, depending on the pumping depth. ,A standardized cable may alsobe used, each unit being provided with a separate cable extending onlyto the respective unit, whereas if a single large unit were employed, acorrespondingly large cable would necessarily extend the full depth.

In Fig. 7 is shown a wiring diagram of interconnected starting and motorprotection circuits for the two motors. Conductors 1|, 12, 13 supplycurrent for both motors from a three-phase supply line, being connectedto a magnetic starting switch 14 for the lower motor l2 through a fuseddisconnect switch 15, and being connected to a similar starting switch18 for the upper motor 41 through branch conductors 1|, 12', 13 and asimilar disconnect switch 11. The starting switch 14 is controlled by apush button station 18, the starting circuit including overload relays19 and 88 in the power conductors to motor I2, overload relays 8| and 82in the power conductors to motor 41, and a common motor protecting relay83. When the push-button switch is closed, current flows from terminal85 of conductor 13 through the push button switch 18, conductor 88,motor protector relay 83, overload relays 88, 8|, 82, and 19 insuccession, through the solenoid 88 of the starting switch 14, and backto the line terminal 89, provided all of the relays are closed.Energization of the solenoid 88 closes the starting switch 14 and motorI2 is energized through leads 9|, 92, 93.

In order to provide a suitable time interval between the starting of thelower motor l2 and the upper motor 41, a time delay relay 95 isconnected by conductors 96 and 91 across the conductors 92 and 93 atterminals 98 and 99 so as to be energized upon starting motor |2. Thisrelay may be of any desired typ providing the required time intervalbefore closing its switch I88. Upon closing the latter, current flowsfrom terminal 98 through conductor 98, conductor |8| leading to thesolenoid I82 of starting switch 16 of the upper motor 41, through thesolenoid I82, conductor I83, switch I88, conductor 91, and terminal 99.Energization of solenoid I82 closes the starting switch 16 to energizethe upper motor 41.

Referring now to the motor protecting circuits, Fig. 2 shows a part ofthe lower portion of motor housing 41 broken away, disclosing a waterlevel indicator H8 and a thermostatic switch III mounted therein. Itwill be understood that well liquid is permitted to enter the lower endof the motor housing to equalize the pressure of the dielectrioliquidtherein with the pressure externally of the housing. If for any reasonthe water level should rise above a predetermined point the water levelindicator I I8 stops the motor by means of the protector relay 83, in amanner to be presently described. The thermostatic switch III isarranged to close if for any reason the temperature of the dielectricliquid should reach a predetermined value, such as would occur if themotor were not properly cooled. An oil test coil I|2 (Fig. 7) is mountedat any suitable point within the motor housing, and functions to stopthe motor if the dielectric strength of the dielectric liquid decreasesa predetermined amount as a result of diffusion of water or otherconducting liquid through the dielectric liquid. A similar water levelindicator I8, thermostatic switch III, and oil test coil I|2 are mountedin the lower motor housing I2.

The indicator 8 and thermostatic switch I are connected to a controlwire N5, the other side of the switch I being grounded to the motorhousing. The test coil 2 is connected at one side to a control wire H8,the other side being grounded to the motor housing. Wires H5 and H8 arehoused within the power conductor cable 8| and. extend to the surfacewhere they are connected respectively to similar control wires 1 and M8for the lower motor I2, the latter wires being housed within conductorcable 2|. At the surface all four control wires are connected to acommon conductor I28 connected to one side of the solenoid |2| of themotor protector relay 83. The other side of the solenoid is connected tothe low voltage side of a transformer I22, which is grounded at |23. Thetransformer is energized through conductors I24, I connectedrespectively to the power conductors 1| and 12.

From the foregoing description, it will be apparent that if the level ofthe well liquid within either motor housing rises to a point that itcontacts the indicator H8 or II8, a circuit will be established fromground I23 through the coil of transformer |22, through solenoid I 2|,conductor I28, conductor H5 or H1 and indicator 8 or ||8' to ground.Energization of solenoid I2| will open the relay 83, breaking thecircuit of the starting switch 14 and stopping motor i2. Deenergizationof motor l2 immediately stops motor 47, since the starting circuit ofthe latter is connected to the leads to motor l2. Similarly, thetemperature of the dielectric liquid in either motor housing should risesuficiently to close either thermostatic switch Hl or iii, the sameresults will follow. If the dielectric strength or" the liquid in eithermotor should decrease sufficiently to permit sumcient current to flowthrough the test coil H2 or 2' to energize the solenoid I21, the motorswill be stopped in the same manner.

It will be noted that the overload relays JED, till, 8! and 82 of bothmotors are all connected in series in the starting circuit of motor 32,so that in the event of excess current flowing to either motor bothmotors will be stopped.

I claim:

1. Deepwell pumping apparatus comprising, in combination: a sectionaldischarge column adapted to be suspended in a well; a first pumpconnected in series between adjacent sections of said column; a secondpump connected to the lower end of said column and having its inlet opento the well; a submersible motor operatively connected to each of saidpumps; each or" said motors comprising a housing exposed externally tothe well pressure and containing a dielectric liquid inpressure-balanced relation to the ambient fluid, a rotor and a statorimmersed in the dielectric liquid in each of said housings, each rotorhaving a rotor shaft projecting from the housing into driving relationwith the respective pump; a liquid seal sealing the juncture of theshaft and housing and being exposed externally to well pressure andinternally to dielectric liquid; and means for cooling the motorassociated with said first pump, comprising a casing surrounding themotor housing and open to the well, and a bleeder con duit extendingfrom said discharge column to said casing for lay-passing liquid fromsaid discharge column in heat excl'lange relation to said motor housingand back to the well.

A suhmersible motor-pump unit adapted to he connected between upper andlower sections of a well discharge column, comprising a pumpconnectilole with the lower end of the upper column section, a suctionpiece for the pump comprising upper and lower coaxial end portions, asuction inlet communicating with the upper end portion, a chamber in thelower end portion having a drain port open to the well, a partitionbetween the suction inlet and the chamber, a submersible motor having ahousing secured to the lower end portion of said suction piece and ashaft extending from the motor through the suction piece and operativelyconnected to the pump, a seal between the shaft and the motor housingand exposed externally to said chamber, a casing surrounding said motorhousing and having open communication with the well, a discharge conduitconnected to said suction inlet and extending downwardly past said motorand connectible at its lower end with the upper end of said lower columnsection, and a bleeder passage extending from said conduit to saidcasing for lay-passing liquid from said column in heat exchange relationto said motor housing and bacl; to the well.

3. A submersible motor-pump assembly comprising: a discharge columnsupported from. the surface and extending downwardly into a well, aconnector secured to the lower end of said column, a multistage deepwellpump secured to said con-= nector, a second connector secured to thelower end of said pump, tension rods extending between said connectors,a motor supported by said second connector, a laterally offset dischargepipe secured to the inlet of said pump and extending downwardly pastsaid motor, a third connector secured to the lower end of said pipe,tension rods extending between said second and third connectors, adischarge column supported by said third connector, and a submersiblemotor-pump unit supported by said last narned discharge column.

ellilDl-llt l-lOLMiNDER.

